1. Field of the Invention
The invention relates to an apparatus for transporting and for conveying fabrics, individual articles and other material, in particular for feeding web-shaped material into a machine which processes it, for example a paper web into a printing machine, with at least one conveyor element formed for engagement with the material, a guide rail, in and/or along which the conveyor element(s) can move, and a drive device comprising the conveyor element in order to convey the material into and/or through the machine via the conveyor element.
2. Description of the Related Art
The paper web is conveyed in a certain direction by means of a driver hook in known paper feed apparatus of approximately this type. The driver hook is fastened to a chain which is moved along a guide in the conveying direction by means of a pneumatic drive. Once the paper web has been fed into the printing machine, the driver hook is disengaged from the paper web and carried manually back to the beginning of the feed region together with its drag chain. Re-engagement with the next paper web is also effected manually. However, because of the pneumatic drive means, the conveying force cannot be controlled or regulated with sufficient accuracy; this results in the risk of the paper web tearing easily, so that the feed operation has to be repeated. A further disadvantage lies in the fact that the driver hook, as a conveyor element, must be manually unhooked and carried back to the beginning of the feed region, which increases expenditure in terms of human labour and working time. In addition, the conveying chain which is connected to the driver hook requires a comparatively high level of maintenance. The "air" employed as the medium in a pneumatic drive is relatively expensive.
DE 41 22 228 C2, DE-PS 20 21 246, DD 263 262 A1 and EP 0 425 741 A1 also disclose web feed apparatus whose drive principle is based on mechanical positive and frictional engagement. This is why, and particularly in view of their numerous mobile parts, they exhibit high friction losses and high wear levels. The large number of moving parts results in a complex construction entailing high costs. The conveying stations in the apparatus according to the last- mentioned source reference require a large amount of space. Finally, the apparatus according to the above-mentioned source references entail the risk of interruptions occurring due just to slight fouling of the guide rails or traction device.
Finally, DE 196 21 507.2 which, although an older patent application, had not been published on the date of filing this application, describes a web feed apparatus for a machine which processes web-shaped material, in particular a web-fed rotary reel printing machine, in which a rail-guided traction device is driven through the direct action of magnetic forces by means of an electric linear drive and pulls the web after it. The traction device virtually forms the rotor of the electric linear drive, and the guide rail for the traction device the stator of this drive, while electrically excitable coils are arranged along the guide rail. The content of this older patent application, presumably subsequently published, is hereby included in the disclosure of the present application.
The object of the invention, with respect to a feed apparatus of the type initially mentioned, is to prevent mechanical wear and friction losses, reduce manufacturing and construction expenditure, enable the feed operation to be fully automated and increase operating safety and reliability.